Solar Energy is the energy provided by the sun, but nowaday solar energy
refers to the process of adapting the sun’s energy arriving on earth surface to useful energy for everyday application. The Sun is the nearest star to earth, its mass is more than 300.000 times earth’s mass, which represents 99% the mass of the whole solar system, and its radius is 119 times earth’s radius, its main component are the hydrogen, about 73%, and helium, around 25% of sun’s mass.
earth’s atmosphere receives 174.000 TeraWatts of energy in form of electromagnetic waves having a spectrum spectrum from near ultraviolet to infrared and in all the visible wavelengths, making the light of the sun as the perfect white light in the universe. in one year the energy of the sun can provide more energy of the whole consumption of the human race since the beginning of the industrial age.
Recent papers have proven that just a small portions the sun’s insolation can provide the annual world consumption in the image bellow found in Wikipedia the little black spots represents the world consumption in one year, in other worlds each of these surfaces receives on a yearly basis the consumption of world in terms of all types of energy.
unfortunately we don’t possess yet an efficient system that would allow us to use all the energy coming from the sun, however, even if we create one in the future, which is likely to happen based on the fast development in this field nowadays, there is another residing in the transportation losses, this energy produced needs to be transported to different parts of the world which is impossible with what we have at this time, another nearly impossible solution is to transfer most of the biggest factories near these spots which will reduce the overall world consumption.
Solar energy is an important if not the main source for renewable energies and can be categorized as active energy through technologies like Photovoltaic plants, Concentrated solar plants or water heating systems, as it can be passive energy by designing building to have maximum sun surface or designing naturally light spreading spaces etc.
Other sources of renewable energies are generated indirectly by the thermal effect of solar insolation on earth surface like wind or waves energy, which are results of thermal gradient happening between two spaces caused by sun.
Exploiting solar energy can be as simple as using convex or glass magnifier to concentrate light in smaller space and create an increase of temperature leading to heat, this simple application can be used to cook food in some regions or to produce high pressure vapor on an industrial scale. another way to use directly the light from the sun, is to heat water using snake form black pipe which will absorb solar irradiance and transform it to heat then with water running in the pipes a thermal exchange will lead to heat the water, by this principle a lot of people in the world take hot showers, but the most profitable way to use solar energy is to use the photovoltaic effect discovered in the early 19th century by the french scientist becquerel, and transform the light to the most used form of energy nowadays: Electricity.
The Photovoltaic Cells also called photovoltaic generators are the basic parts of a PV system which converts incident light to current, a PV panel is made of number of cells in series and parallel to produce higher current and voltage thus higher power. The solar radiation that fills our sky can be direct, diffuse or reflected radiation.
- Direct radiation is also sometimes called “beam radiation” or “direct beam radiation”. It is used to describe solar radiation traveling on a straight line from the sun down to the surface of the earth.
- Diffuse radiation, on the other hand, describes the sunlight that has been scattered by molecules and particles in the atmosphere but that has still made it down to the surface of the earth.
- Reflected radiation, is the sunlight that have been reflected by obstacles or earth itself.
Direct and Reflected radiation has a definite direction but diffuse radiation is just going any which way. Because when the radiation is direct, the rays are all travelling in the same direction, an object can block them all at once. This is why shadows are only produced when direct radiation is blocked.